GaAs Solar Cells on V-Grooved Silicon via Selective Area Growth

Interest in integrating III-Vs onto Si has recently resurged as a promising pathway towards high-efficiency, lowcost tandem photovoltaics. Here, we present single-junction GaAs solar cells grown monolithically on on-axis Si (001) substrates using V-grooves, selective area growth, and aspect ratio trapping to mitigate defect formation without the use of expensive, thick graded buffers, along with homoepitaxially grown GaAs solar cell test structures. The GaAs buffer grown directly on Si is free of antiphase domains and exhibits a relatively low TDD of 4×107 cm-2, despite the lack of a graded buffer. These demonstration solar cells show promise for further improvements to III-V/Si tandems to enable cost-competitive photovoltaics.